Power conversion device

ABSTRACT

A power conversion device is provided. The power conversion device includes N power conversion circuits and M magnetic components, where N and M are positive integers greater than 1. Each of the N power conversion circuits includes M inductors. DC currents flowing through the M inductors respectively are unequal. Each one of the M inductors in different ones of the N power conversion circuits corresponds to each other to form a group of N corresponding inductors. In the N power conversion circuits, DC currents respectively flowing through the corresponding inductors are equal. Each of the M magnetic components includes a middle pillar, N side pillars and two substrates. The middle pillar has an air gap. In the N power conversion circuits, windings of N corresponding inductors are respectively wound around the N side pillars of one of the M magnetic components.

RELATED APPLICATION

This application claims priority to China Patent Application No.202010234598.6, filed on Mar. 30, 2020. The entire contents of theabove-mentioned patent application are incorporated herein by referencefor all purposes.

TECHNICAL FIELD

The present disclosure relates to a power conversion device. Moreparticularly, the present disclosure relates to a power conversiondevice capable of counteracting the DC magnetic fluxes generated by thewindings of inductors.

BACKGROUND

In conventional non-isolated step-down applications with large current,a multi-phase asymmetric buck circuit topology is used to improve thepower conversion efficiency. Specifically, in each phase of theasymmetric buck circuit, the windings of plural inductors are woundaround the side pillars of the same magnetic component. Accordingly, theAC magnetic fluxes on the middle pillar of the magnetic component can becounteracted with each other, thereby reducing the ripple of the outputcurrent. However, if the DC currents flowing through the pluralinductors are unequal, the DC magnetic fluxes on the side pillars wouldbe large, which makes the magnetic core easy to be saturated.

Therefore, there is a need of providing a power conversion device toobviate the drawbacks encountered from the prior arts.

SUMMARY

It is an objective of the present disclosure to provide a powerconversion device. In a plurality of power conversion circuits, the DCcurrents flowing through the corresponding inductors which arecorresponding to each other are equal. The windings of thesecorresponding inductors are wound around the side pillars of the samemagnetic component, thus the DC magnetic fluxes on the side pillars canbe counteracted by each other without disposing an air gap on the sidepillars. Consequently, the loss of the power conversion device isreduced, and the magnetic core is prevented from being saturated easily.

In accordance with an aspect of the present disclosure, there isprovided a power conversion device. The power conversion device includesan input port, an output port, N power conversion circuits and Mmagnetic components, where N and M are positive integers greater than 1.The N power conversion circuits are electrically connected between theinput and output ports in parallel. Each of the N power conversioncircuits includes M inductors. DC currents flowing through the Minductors respectively are unequal. The M inductors include at least onecorresponding inductor. In the N power conversion circuits, DC currentsflowing through the corresponding inductors which are corresponding toeach other are equal. Each of the M magnetic components includes amiddle pillar, N side pillars and two substrates. The middle pillar andthe N side pillars are located between the two substrates. The middlepillar has an air gap. In the N power conversion circuits, windings of Ncorresponding inductors which are corresponding to each other are woundaround the N side pillars of one of the M magnetic components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit diagram illustrating a power conversiondevice according to a first embodiment of the present disclosure;

FIG. 2A and FIG. 2B are schematic views showing the structure of amagnetic component in the first embodiment of the present disclosure;

FIG. 3A and FIG. 3B are schematic views showing the winding manner ofinductors in the first embodiment of the present disclosure;

FIG. 4 is a schematic circuit diagram illustrating a power conversiondevice according to a second embodiment of the present disclosure; and

FIG. 5A and FIG. 5B are schematic views showing the structure of amagnetic component in the second embodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described in more detail withreference to the accompanying drawings. It is to be noted that thefollowing descriptions are presented herein for illustrative purposesonly. It is not intended to be exhaustive or to be limited to theprecise form disclosed.

FIG. 1 is a schematic circuit diagram illustrating a power conversiondevice 100 according to a first embodiment of the present disclosure.FIG. 2A and FIG. 2B are schematic views showing the structure of amagnetic component 120 in the first embodiment of the presentdisclosure. As shown in FIGS. 1, 2A, and 2B, the power conversion device100 of the present disclosure includes an input port Vin, an output portVo, N power conversion circuits 110 and M magnetic components 120, whereboth N and M are positive integers greater than 1.

The N power conversion circuits 110 are connected to each other inparallel and are electrically connected between the input port Vin andthe output port Vo. Each of the N power conversion circuits 110 includesM inductors, and the currents flowing through the M inductorsrespectively are unequal. The M inductors in one of the N powerconversion circuits 110 can correspond to at least one inductor inanother one of the N power conversion circuits 110. In the N powerconversion circuits 110, the currents flowing through the correspondinginductors which are corresponding to each other are equal.

As shown in FIGS. 2A and 2B, each of the M magnetic components 120includes a middle pillar 25, N side pillars 21, 22 (here, N=2), and twosubstrates 23, 24. The middle pillar 25 and the N side pillars 21, 22are located between the two substrates 23, 24. The middle pillar has anair gap 26 that makes the equivalent reluctance of the middle pillarlarger. In the N power conversion circuits 110, the windings of the Ncorresponding inductors which are corresponding to each other are woundaround the N side pillars 21, 22 of the same magnetic component with thesame winding direction. Consequently, with regard to each of the N sidepillars 21, 22 of the magnetic component, the DC magnetic fluxes flowingtherethrough are counteracted by each other. Moreover, the DC magneticfluxes are superimposed on the middle pillar 25, thereby preventing themagnetic core of the magnetic component from being saturated easily.Further, since the air gap 26 only exist on the middle pillar 25, theinductance of the corresponding inductor can be increased, and theoutput current ripple and loss of the power conversion device 100 arereduced. In addition, in an embodiment, the voltage signals on the Ncorresponding inductors wound around the same magnetic component are outof phase with respect to each other in sequence by an angle between(360/N+30) degrees and (360/N+30) degrees. Therefore, the AC magneticfluxes on the middle pillar 25 of the magnetic component can becounteracted by each other.

In order to control the switches of the power conversion circuit 110,the power conversion device 100 further includes a controller 101. Thecontroller output N control signals that are configured to control the Npower conversion circuits 110 respectively. The N control signals havethe same duty ratio. The N control signals may be at the same phase.Alternatively, the N control signals may be output of phase with respectto each other in sequence by an angle between (360/N−30) degrees and(360/N+30) degrees.

In an embodiment, each power conversion circuit includes M powerconversion units, and each of the M power conversion units includes aninductor, a first switch and a second switch serially connected to thefirst switch. The first switch of the first power conversion unit isconnected to the input port Vin, and the first switch of other powerconversion unit is connected to the first switch of the preceding powerconversion unit in sequence. In an embodiment, the N control signalscontrol the first switches of the first power conversion units of the Npower conversion circuit respectively. In each power conversion circuit,the control signals of the M first switches of the M power conversionunits have the same duty ratio and are 360/M degrees out of phase withrespect to each other. Moreover, in each power conversion unit, thecontrol signals of the first and second switches are complementary toeach other.

In accordance with the first embodiment shown in FIG. 1, FIG. 2A andFIG. 2B, the actual implementation with N equal to 2 and M equal to 2 isexemplified as follows.

In the first embodiment shown in FIG. 1, the power conversion device 100includes two power conversion circuits X1 and X2. In this embodiment,the power conversion circuit X1 is connected to the input capacitor Cin1in parallel, and the power conversion circuit X2 is connected to theinput capacitor Cin2 in parallel, but not exclusively. In anotherembodiment, the power conversion circuits X1 and X2 may be connected tothe same input capacitor in parallel. The output port Vo of the powerconversion device 100 is formed by connecting the output capacitor Co tothe output terminals of the power conversion circuits X1 and X2 inparallel. The power conversion circuit X1 includes two power conversionunits. The first power conversion unit includes a first switch M11, asecond switch M13 and an inductor L11, and the second power conversionunit includes a first switch M12, a second switch M14 and an inductorL12. The power conversion circuit X2 includes two power conversionunits. The first power conversion unit of the power conversion circuitX2 includes a first switch M21, a second switch M23 and an inductor L21,and the second power conversion unit of the power conversion circuit X2includes a first switch M22, a second switch M24 and an inductor L22.

The controller 101 outputs two control signals PWM1 and PWM2 to controlthe two power conversion circuits X1 and X2, respectively. The controlsignals PWM1 and PWM2 have the same duty ratio. The control signals PWM1and PWM2 may be at the same phase, or the control signals PWM1 and PWM2may be out of phase with respect to each other in sequence by an anglebetween 150 degrees and 210 degrees. For example but not exclusively,the control signals PWM1 and PWM2 may be pulse width modulation signals.In the power conversion circuit X1, the first switch M11 is controlledby the control signal PWM1, and the control signal of the first switchM12 and the control signal PWM1 have the same duty ratio and are 180degrees out of phase with respect to each other. The control signal ofthe second switch M13 is complementary to the control signal PWM1, andthe control signal of the second switch M14 is complementary to thecontrol signal of the first switch M12. In the power conversion circuitX2, the first switch M21 is controlled by the control signal PWM2, andthe control signal of the first switch M22 and the control signal PWM2have the same duty ratio and are 180 degrees out of phase with respectto each other. The control signal of the second switch M23 iscomplementary to the control signal PWM2, and the control signal of thesecond switch M24 is complementary to the control signal of the firstswitch M22.

In the two power conversion circuits X1 and X2, when the duty ratio ofthe two control signals PWM1 and PWM2 are greater than 50%, the DCcurrents flowing through the inductors L11 and L12 respectively areunequal, and the DC currents flowing through the inductors L21 and L22respectively are unequal. The two inductors L11 and L12 of the powerconversion circuit X1 are a first corresponding inductor and a secondcorresponding inductor respectively. The two inductors L21 and L22 ofthe power conversion circuit X2 are a first corresponding inductor and asecond corresponding inductor respectively. The DC currents flowingthrough the two first corresponding inductors (i.e., the inductors L11and L21), which are corresponding to each other, are equal. The DCcurrents flowing through the two second corresponding inductors (i.e.,the inductors L12 and L22), which are corresponding to each other, areequal. It is noted that the description about the DC currents beingequal or unequal means that the DC currents are substantially equal orunequal. For example, the DC currents are equal if the difference ratiotherebetween is less than or equal to 20%, and the DC currents areunequal if the difference ratio therebetween is greater than 20%. Thefollowing description about the DC currents being equal or unequal meansthe same. In addition, the windings of the two first correspondinginductors (i.e., the inductors L11 and L21) are wound around themagnetic component 2 a of FIG. 2A, and the winding directions of theinductors L11 and L21 are the same. The windings of the two secondcorresponding inductors (i.e., the inductors L12 and L22) are woundaround the magnetic component 2 b of FIG. 2B, and the winding directionsof the inductors L12 and L22 are the same. However, the actual windingdirections of the inductors are not limited to that shown in thedrawings.

As shown in FIG. 2A, the magnetic component 2 a includes two sidepillars 21 and 22, two substrates 23 and 24 and a middle pillar 25. Themiddle pillar 25 and the side pillars 21 and 22 are located between thetwo substrates 23 and 24. The middle pillar 25 has an air gap 26. Inthis embodiment, side pillars 21, 22 and middle pillar 25 have arectangular rail or bar shape. The winding of the inductor L11 is woundaround the side pillar 21, and the winding of the inductor L21 is woundaround the side pillar 22. The winding directions of the inductors L11and L21 are the same, but not limited to that shown in the drawings. TheDC magnetic flux generated by the inductor L11 on the side pillar 21 isrepresented by Φ11. The DC magnetic flux Φ11 may flow toward the sidepillar 22 and the middle pillar 25. The part of the DC magnetic flux Φ11flowing toward the side pillar 22 is represented by Φ(11-1), and thepart of the DC magnetic flux Φ11 flowing toward the middle pillar 25 isrepresented by Φ(11-2). The DC magnetic flux generated by the inductorL21 on the side pillar 22 is represented by Φ21. The DC magnetic fluxΦ21 may flow toward the side pillar 21 and the middle pillar 25. Thepart of the DC magnetic flux Φ21 flowing toward the side pillar 21 isrepresented by Φ(21-1), and the part of the DC magnetic flux Φ21 flowingtoward the middle pillar 25 is represented by Φ(21-2). Since the middlepillar 25 has an air gap 26, the equivalent reluctance of the middlepillar 25 is large, which causes the DC magnetic flux flowing toward themiddle pillar 25 to be smaller.

According to Ohm's law for magnetic circuits, Φ11=Nt*I11/Rm1, andΦ(21-1)=Nt*I21/Rm1. Nt is the winding turns of the inductors L11 and L21(as an example, the inductors L11 and L21 have the same winding turns).I11 is the DC current flowing through the inductor L11. I21 is the DCcurrent flowing through the inductor L21. Rm1 is the equivalentreluctance of the side pillars 21 and 22 (as an example, the sidepillars 21 and 22 have the same equivalent reluctance). Therefore, theDC magnetic flux on the side pillar 21 equalsΦ11−Φ(21-1)=Nt*(I11−I21)/Rm1. Since the DC currents flowing through theinductors L11 and L21 are equal, i.e., I11=I21, Φ11 is equal to Φ(21-1),the DC magnetic fluxes on the side pillar 21 are therefore counteractedby each other. Consequently, it is allowed to employ small reluctanceRm1, namely, there is no need to form air gap on the side pillar 21,which can increase the inductance of the inductor L11 and reduces theoutput current ripple and loss of the power conversion device 100.

It is noted that the counteraction of the magnetic flux does not meanthat the magnetic flux is zero. For example, there may be a residualmagnetic flux after counteracting magnetic flux, and the amount of theresidual magnetic flux is determined by the difference between thecurrents flowing through the corresponding inductors. The flowingdescription about the counteraction of magnetic flux means the same.

Similar to the magnetic fluxes on the side pillar 21, the magneticfluxes on the side pillar 22 are counteracted by each other withoutforming air gap on the side pillar 22. Therefore, the inductance of theinductor L21 can be increased, and the output current ripple and loss ofthe power conversion device 100 can be reduced. Also, the DC magneticfluxes on the substrates are counteracted by each other. Consequently,the thickness of the substrates 23 and 24 can be decreased. As a result,the size of the magnetic component 2 a can be reduced.

In an embodiment, through the control signals PWM1 and PWM2 being out ofphase with respect to each other, the voltage signals on the inductorsL11 and L21 may be out of phase with respect to each other by an anglebetween 150 degrees and 210 degrees (for example but not limited to 180degrees). Consequently, the AC magnetic fluxes on the middle pillar 25of the magnetic component 2 a are counteracted by each other, which canincrease the equivalent inductances of the inductors L11 and L21 andreduce the ripple of the output current.

For the same reason, in FIG. 2B, the windings of the inductors L12 andL22 are wound around the side pillars 21 and 22 of the magneticcomponent 2 b respectively. The counteraction of DC magnetic flux isachieved on the side pillars 21 and 22 of the magnetic component 2 b.The elements of the magnetic component 2 b which are similar to that ofthe magnetic component 2 a are designated by identical numeralreferences, the counteraction principle for the magnetic component 2 bis the same as that for the magnetic component 2 a, and thus thedetailed descriptions thereof are omitted herein. In an embodiment,through the control signals PWM1 and PWM2 being out of phase withrespect to each other, the voltage signals on the inductors L12 and L22may be out of phase with respect to each other by an angle between 150degrees and 210 degrees (for example but not limited to 180 degrees).Consequently, the AC magnetic fluxes on the middle pillar 25 of themagnetic component 2 b are counteracted by each other, which canincrease the equivalent inductances of the inductors L12 and L22 andreduce the ripple of the output current.

FIG. 3A illustrates a winding manner of the inductors L11 and L21 inaccordance with an embodiment of the present disclosure. FIG. 3Billustrates the winding manner of the inductors L12 and L22 inaccordance with an embodiment of the present disclosure. As shown inFIGS. 3A and 3B, the preconditions are winding the windings of thecorresponding inductors (e.g., L12 and L22) on different side pillars ofthe same magnetic component, thereby allowing the DC magnetic fluxes onthe side pillars to be counteracted by each other without forming airgap on the side pillar. It is to be appreciated that, so long as thepreconditions are satisfied, the winding position of the inductors, theentire structure of the magnetic components 2 a and 2 b and the shapeand size of the side and middle pillars of the magnetic components 2 aand 2 b can be adjusted according to actual requirements without beinglimited to the exemplified manner as shown in the drawings.

For example but not exclusively, the magnetic component (2 a, 2 b) canbe formed by two magnetic cores assembled together. In an embodiment,one magnetic core may have a first substrate, the middle pillar 25 andthe side pillars 21 and 22 formed on the first substrate, while theother magnetic core may have a second substrate without any pillars. Inanother embodiment, one magnetic core may have a first substrate, a partof the middle pillar 25 and a part of the side pillars 21 and 22 formedon the first substrate, while the other magnetic core may have a secondsubstrate, the other part of the middle pillar 25 and the other part ofthe side pillars 21 and 22 formed on the second substrate.

FIG. 4 is a schematic circuit diagram illustrating a power conversiondevice 200 according to a second embodiment of the present disclosure.FIG. 5A and FIG. 5B are schematic views showing the structure of amagnetic component in the second embodiment of the present disclosure.In accordance with the second embodiment shown in FIG. 4, FIG. 5A andFIG. 5B, the actual implementation with N equal to 4 and M equal to 2 isexemplified as follows. Compared with the first embodiment, the secondembodiment can further increase the load capacity of the powerconversion device.

In the second embodiment shown in FIG. 4, the power conversion device200 includes four power conversion circuits X1, X2, X3 and X4. In thisembodiment, the power conversion circuit X1 is connected to the inputcapacitor Cin1 in parallel; the power conversion circuit X2 is connectedto the input capacitor Cin2 in parallel; the power conversion circuit X3is connected to the input capacitor Cin3 in parallel; and the powerconversion circuit X4 is connected to the input capacitor Cin4 inparallel, but not exclusively. In another embodiment, the powerconversion circuits X1, X2, X3 and X4 may be connected to the same inputcapacitor in parallel. The output port Vo of the power conversion device200 is formed by connecting the output capacitor Co to the outputterminals of the power conversion circuits X1, X2, X3 and X4 inparallel.

The components of the power conversion circuits X1 and X2 in the secondembodiment are the same as that in the first embodiment, thus thedetailed descriptions thereof are omitted herein. The power conversioncircuit X3 includes two power conversion units. The first powerconversion unit of the power conversion circuit X3 includes a firstswitch M31, a second switch M33 and an inductor L31. The second powerconversion unit of the power conversion circuit X3 includes a firstswitch M32, a second switch M34 and an inductor L32. The powerconversion circuit X4 includes two power conversion units. The firstpower conversion unit of the power conversion circuit X4 includes afirst switch M41, a second switch M43 and an inductor L41. The secondpower conversion unit of the power conversion circuit X4 includes afirst switch M42, a second switch M44 and an inductor L42.

The controller 201 output four control signals PWM1, PWM2, PWM3 and PWM4to control the four power conversion circuits X1, X2, X3 and X4respectively. The control signals PWM1, PWM2, PWM3 and PWM4 have thesame duty ratio. The control signals PWM1, PWM2, PWM3 and PWM4 may be atthe same phase, or the control signals PWM1, PWM2, PWM3 and PWM4 may beout of phase with respect to each other in sequence by an angle between60 degrees and 120 degrees. For example but not exclusively, the controlsignals PWM1, PWM2, PWM3 and PWM4 are pulse width modulation signals.

The control manner for the power conversion circuits X1 and X2 in thesecond embodiment is the same as that in the first embodiment, and thedetailed descriptions thereof are omitted herein. In the powerconversion circuit X3, the first switch M31 is controlled by the controlsignal PWM3, and the control signal of the first switch M32 and thecontrol signal PWM3 have the same duty ratio and are 180 degrees out ofphase with respect to each other. The control signal of the secondswitch M33 is complementary to the control signal PWM3, and the controlsignal of the second switch M34 is complementary to the control signalof the first switch M32. In the power conversion circuit X4, the firstswitch M41 is controlled by the control signal PWM4, and the controlsignal of the first switch M42 and the control signal PWM4 have the sameduty ratio and are 180 degrees out of phase with respect to each other.The control signal of the second switch M43 is complementary to thecontrol signal PWM4, and the control signal of the second switch M44 iscomplementary to the control signal of the first switch M42.

In the four power conversion circuits X1, X2, X3 and X4, when the dutyratio of the four control signals PWM1, PWM2, PWM3 and PWM4 are greaterthan 50%, the DC currents flowing through the inductors L11 and L12respectively are unequal, the DC currents flowing through the inductorsL21 and L22 respectively are unequal, the DC currents flowing throughthe inductors L31 and L32 respectively are unequal, and the DC currentsflowing through the inductors L41 and L42 respectively are unequal. Thetwo inductors L11 and L12 of the power conversion circuit X1 are a firstcorresponding inductor and a second corresponding inductor respectively.The two inductors L21 and L22 of the power conversion circuit X2 are afirst corresponding inductor and a second corresponding inductorrespectively. The two inductors L31 and L32 of the power conversioncircuit X3 are a first corresponding inductor and a second correspondinginductor respectively. The two inductors L41 and L42 of the powerconversion circuit X4 are a first corresponding inductor and a secondcorresponding inductor respectively.

The DC currents flowing through the four first corresponding inductors(i.e., the inductors L11, L21, L31 and L41), which are corresponding toeach other, are equal. The DC currents flowing through the four secondcorresponding inductors (i.e., the inductors L12, L22, L32 and L42),which are corresponding to each other, are equal. In addition, thewindings of the four first corresponding inductors (i.e., the inductorsL11, L21, L31 and L41), which are corresponding to each other, are woundaround the magnetic component 3 a of FIG. 5A, and the winding directionsof the inductors L11, L21, L31 and L41 are the same (e.g.,counterclockwise). The windings of the four second correspondinginductors (i.e., the inductors L12, L22, L32 and L42), which arecorresponding to each other, are wound around the magnetic component 3 bof FIG. 5B, and the winding directions of the inductors L12, L22, L32and L42 are the same (e.g., counterclockwise). However, the actualwinding directions of the inductors are not limited to that shown in thedrawings.

FIG. 5A and FIG. 5B show the partial structures of the magneticcomponents 3 a and 3 b respectively.

As shown in FIG. 5A, the magnetic component 3 a includes a middle pillar30, four side pillars 31, 32, 33 and 34, and two substrates (only onesubstrate 35 is shown in FIG. 5A). The middle pillar 30 and the fourside pillars 31, 32, 33 and 34 are located between the two substrates.In this embodiment, the middle pillar 30 and side pillars 31, 32, 33, 34have a cylindrical shape. It is appreciated that middle pillar 30 andside pillars 31, 32, 33, 34 can have any other suitable shapes, such as,a triangular prism shape, a rectangular prism shape, a hexagonal prismshape, etc. The four side pillars 31, 32, 33 and 34 are disposed aroundthe middle pillar 30. The middle pillar 30 has an air gap (not shown).The windings of the inductor L11, L21, L31 and L41 are wound around theside pillars 31, 32, 33 and 34. The winding directions of the inductorsL11, L21, L31 and L41 are the same (e.g., counterclockwise), but notlimited to that shown in the drawings. Accordingly, the counteraction ofDC magnetic flux is achieved on the four side pillars 31, 32, 33 and 34,the counteraction principle can be derived from the first embodiment,and the detailed descriptions thereof are thus omitted herein.

In an embodiment, through the control signals PWM1, PWM2, PWM3 and PWM4being out of phase with respect to each other, the voltage signals onthe inductors L11, L21, L31 and L41 may be out of phase with respect toeach other by an angle between 60 degrees and 120 degrees (for examplebut not limited to 90 degrees). Consequently, the AC magnetic fluxes onthe middle pillar 30 are counteracted by each other, which can increasethe equivalent inductances of the inductors L11, L21, L31 and L41 andreduce the ripple of the output current.

For the same reason, in FIG. 5B, the windings of the inductors L12, L22,L32 and L42 are wound around the side pillars 31, 32, 33 and 34 of themagnetic component 3 b with the same winding direction (e.g.,counterclockwise). The counteraction of DC magnetic flux is achieved onthe side pillars 31, 32, 33 and 34 of the magnetic component 3 b. Theelements of the magnetic component 3 b which are similar to that of themagnetic component 3 a are designated by identical numeral references,the counteraction principle for the magnetic component 3 b is the sameas that for the magnetic component 3 a, and thus the detaileddescriptions thereof are omitted herein. In an embodiment, through thecontrol signals PWM1, PWM2, PWM3 and PWM4 being out of phase withrespect to each other, the voltage signals on the inductors L12, L22,L32 and L42 may be out of phase with respect to each other by an anglebetween 60 degrees and 120 degrees (for example but not limited to 90degrees). Consequently, the AC magnetic fluxes on the middle pillar 30are counteracted by each other, which can increase the equivalentinductances of the inductors L12, L22, L32 and L42 and reduce the rippleof the output current.

From the above descriptions, the present disclosure provides a powerconversion device. In a plurality of power conversion circuits, the DCcurrents respectively flowing through the corresponding inductors areequal. The windings of these corresponding inductors are wound aroundthe side pillars of the same magnetic component, thus the DC magneticfluxes on the side pillars can be counteracted by each other withoutforming an air gap on the side pillars. Consequently, the loss of thepower conversion device is reduced, and the magnetic core is preventedfrom being saturated easily. Moreover, the DC magnetic fluxes on thesubstrates are counteracted by each other. Therefore, the thickness ofthe substrates can be decreased, and the size of the magnetic componentcan be reduced.

While the present disclosure has been described in terms of what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the claimed scope of the present disclosureneeds not be limited to the disclosed embodiments.

What is claimed is:
 1. A power conversion device, comprising: an inputport and an output port; N power conversion circuits electricallyconnected between the input and output ports in parallel, each of the Npower conversion circuits comprising M inductors with unequal DCcurrents respectively flowing through the M inductors in each of the Npower conversion circuits, each one of the M inductors in different onesof the N power conversion circuits corresponding to each other to form agroup of N corresponding inductors with equal DC currents respectivelyflowing through the N corresponding inductors, wherein N and M arepositive integers greater than 1; and M magnetic components, each of theM magnetic components comprising a middle pillar, N side pillars and twosubstrates, the middle pillar and the N side pillars being locatedbetween the two substrates, the middle pillar having an air gap, whereinin the N power conversion circuits, windings of the N correspondinginductors are respectively wound around the N side pillars of each ofthe M magnetic components.
 2. The power conversion device according toclaim 1, wherein in the N power conversion circuits, voltage signals onthe N corresponding inductors which are wound around the same magneticcomponent are out of phase with respect to each other by an anglebetween (360/N−30) degrees and (360/N+30) degrees.
 3. The powerconversion device according to claim 1, wherein each of the N powerconversion circuit comprises M power conversion units, each of the Mpower conversion units comprises a first switch, a second switchserially coupled to the first switch, and one of the M inductors, thefirst switch of the first power conversion unit is connected to theinput port, and the first switch of another power conversion unit isconnected to the first switch of a preceding one of the power conversionunits in sequence.
 4. The power conversion device according to claim 3,further comprising a controller, wherein the controller outputs Ncontrol signals to control the N power conversion circuits, the Ncontrol signals having the same duty ratio.
 5. The power conversiondevice according to claim 4, wherein the N control signals areconfigured to control the first and second switches of the powerconversion units of the N power conversion circuits respectively,wherein in each of the N power conversion circuits, the control signalsof the M first switches of the M power conversion units have the sameduty ratio and are 360/M degrees out of phase with respect to each otherin sequence, and control signals of the first and second switches arecomplementary to each other.
 6. The power conversion device according toclaim 4, wherein the N control signals are at the same phase.
 7. Thepower conversion device according to claim 4, wherein the N controlsignals are out of phase with respect to each other in sequence by anangle between (360/N−30) degrees and (360/N+30) degrees.
 8. The powerconversion device according to claim 4, wherein the duty ratio of the Ncontrol signals is larger than 50%.
 9. The power conversion deviceaccording to claim 1, wherein each of the M magnetic components isformed by two magnetic cores assembled together.
 10. The powerconversion device according to claim 9, wherein one of the two magneticcores has one of the two substrates, the middle pillar and the N sidepillars, and wherein the other one of the two magnetic cores has theother one of the two substrates, the middle pillar having an air gap.11. The power conversion device according to claim 9, wherein one of thetwo magnetic cores has one of the two substrates, a part of the middlepillar and a part of the N side pillars, and wherein the other one ofthe two magnetic cores has the other one of the two substrates, theother part of the middle pillar and the other part of the N sidepillars, at least a part of the middle pillar having an air gap.
 12. Thepower conversion device according to claim 1, wherein in each of the Mmagnetic components, DC magnetic fluxes are generated by the Ncorresponding inductors wound around the N side pillars, the DC magneticfluxes are superimposed on the middle pillar, and the DC magnetic fluxeson each of the N side pillars are counteracted by each other.
 13. Thepower conversion device according to claim 1, wherein, in the N powerconversion circuits, windings of the N corresponding inductors arerespectively wound around the N side pillars of each of the M magneticcomponents with the same winding direction.
 14. A power converter,comprising: an input port and an output port; a first quantity of powerconversion circuits electrically wired in parallel between the input andoutput ports; and a second quantity of magnetic components, each of themagnetic components having at least a first substrate, a first centralpillar on the first substrate, and the first quantity of first sidepillars on the first substrate; wherein each of the power conversioncircuits comprises a third quantity of inductors, each of the inductorsbeing magnetically coupled to a respective one of the first side pillarsof a respective one of the magnetic components; and wherein DC currentsrespectively flowing through the inductors in each of the powerconversion circuits are not equal and wherein DC currents respectivelyflowing through the inductors magnetically coupled to a same one of themagnetic components are equal.
 15. The power converter device of claim14, wherein each of the magnetic components further comprises a secondsubstrate disposed on the first substrate, such that the first centralpillar forms an air gap between the first and second substrates and thatthe second substrate contacts the first side pillars without forming anair gap.
 16. The power converter of claim 14, wherein each of themagnetic components further comprises a second substrate, a secondcentral pillar on the second substrate, and the first quantity of secondside pillars on the second substrate, and wherein the second substrateis disposed on the first substrate, such that the first and secondcentral pillars form an air gap between the first and second substrates,and that the first side pillars contact the second side pillars withoutforming an air gap.
 17. The power converter of claim 14, wherein thefirst central pillar includes an air gap.
 18. The power converter ofclaim 14, wherein the first central pillar has one of a rectangular railshape, a cylindrical shape, a triangular prism shape, a rectangularprism shape, and a hexagonal prism shape.
 19. The power converter ofclaim 14, wherein each of the first side pillars has one of arectangular rail shape, a cylindrical shape, a triangular prism shape, arectangular prism shape, and a hexagonal prism shape.
 20. The powerconverter of claim 14, wherein, in each of the magnetic components, DCmagnetic fluxes generated by the inductors are superimposed in the firstcentral pillar and are counteracted with each other in each of the firstside pillars.
 21. The power converter of claim 14, wherein the thirdquantity is equal to the second quantity.